Railway traffic controlling apparatus



Oct. 17, i939.A c. L. oTT

U RAILWAY TRAFFIC CONTROLLING APPARATUS Filed May 25, 1937 3 Sheets-Sheet l.

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RAILWAY TRAFFIC CONTROLLING APPARATUS Filed May 25, 1937 Nm@ @www @awww R .Y mw .mi o mam y cv BH U www Oct. 17, 1939. 01T 2,176,273 RAILWAY TRAFFIC CONTROLLING APPARATUS Filed May 25, 193'? .'5 Sheets-Sheet 3 HEM Wm Uf m m6 TIL will.

Patented ct. 17, 193

PATENT OFFICE RAILWAY TRAFFIC CONTROLLING APPARATUS Clyde L. Ott, Chicago, Ill., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application May 25, 1937,- Serial No. 144,655

6 Claims.

My invention relates to railway traffic controlling apparatus, and particularly to apparatus of the type involving signals which are controlled jointly by devices automatically responsive to trafiic conditions and apparatus manually controlled from a central station through the medium of -line circuits.

A feature of my invention is the provision of novel and improved apparatus responsive to a failure of a controlling line circuit for removing a signal from the control of remotely controlled apparatus governed by such line circuit and allowing such signal to function automatically. Another feature of my invention is the provision of apparatus for a centralized traic control or C. T. C. signal system which, upon failure of the controlling line circuit, automatically switches the signals for operation as an automatic signal system. A still further feature of my invention is the provision in systems of the type here under consideration of novel means for restoring the C. T. C system to normal operation subsequent to reclosing of the controlling line circuit. Again, a feature of the invention is the provision of means wherewith the operator of a C. T. C. system may cause the signals to be operated as an automaticy system. An additional feature of the invention is the provision of means to rindicate to trainmen when the control of the remote operator is removed and they are operating under automatic signal protection only. Other features and advantages of my invention willfappear as the specication progresses.

I shall describe several forms of apparatus embodying my invention, and shall then point out the novel features thereof in claims.

In present day signaling, it is common practice to subordinate automatic cab signals and wayside signals to manual control to the extent that an operator at a central station may hold the trains or indicate the movement they should make while at the same time permitting the signaling indications to reflect traffic conditions.

- In otherwords, the automatic cab or wayside signal system provides the required safety, but the operator may intervene to regulate the train movements that could be made with safety. With such centralized control there exists the possibility of delay and interruption to traffic in the case of a broken line wire or the complete wiping out of a stretch of line by a storm or other hazard, which immediately destroys centralized control operation and usually also destroys communicating facilities. According to my invention, the signals are automatically removed from control of the remotely controlled apparatus upon failure of a line circuit, with the result that little or no delay to trafiic follows a line circuit failure. The centralized control operation is put back into operation subsequent to the reclosing of the line circuit when proper steps have been taken by the operator at the central office.

Although the present invention, in whole or in part, may be applied to any suitable type of cab and wayside signal system either for a single track or a multiple track railway, the invention has been shown applied to a type of wayside signal system for a single track-generally known as the absolute permissive block signal system or A. P. B. system. Furthermore, the invention may be applied to any suitable type of centralized traffic control or C. T. C. system and is disclosed as applied to a circuit code type of C. T. C. system. The invention may be applied to any selected stretch of the signal system.

In the accompanying drawings, Figs. 1a and 1b, when placed end to end with Fig. la at the left-hand side, constitute a diagrammatic vlew of one form of apparatus embodying my invention applied to a C. T. C. system for a stretch o1' single track railway including a passing siding. Figs. 2, 3 and 4 are diagrammatic views of diierent forms of apparatus for detecting the integrity of the controlling line wires of the apparatus of Figs. la and 1b, and which different forms of apparatus each embody the invention. In each of the several views, like reference characters designate similar parts.

Referring to Figs, 1a, and 1b, when taken together with Fig. la at the left, the reference characters Ila and IIb designate the track rails of a stretch of single track railway, the main track MT of which is provided with a passing siding PS connected with the main track MT by track switches BSW and SSW. A train movement from the left to right through this stretch of track is assumed to be an eastbound movement, and a movement from right to left is assumed to be a westbound movement.

At each end of the passing siding PS are located four signals governing traffic in both directions on the main track and onto and oi the siding. At switch BSW, the signal GRU. governs eastbound traific on the main track MT and the signal SRD governs traffic into the siding PS. Signal BLa governs main track westbound traine and signal GLC governs traffic leaving the siding. At switch BSW, the signals 8R41 and BLa govern east and westbound traiiic on the main track, respectively, and the signals 8Lb and 8Rc govern movements into and out of the passing siding, respectively. The signals BLa, ELc, BRar and 8Rc are commonly called starting signals, and the signals 6R11, BRU, BLa and Lb` are called entrance signals. l

In addition to the signals at the two ends of Vthe passing sidingr PS, as above described, there may be intermediate signals arranged in pairs or in staggered relation, in accordance with usual practice. In Fig. la, a pair of opposite intermediate signals l and 2 is illustrated for governing west and eastbound traflic, respectively. In Fig. 1b, a pair of opposite intermediate signals Band l is also illustrated.

These wayside signals may be of any desired construction, either semaphore, positionI light or color light, and are illustrated conventionally by symbols commonly used in the art,

The track rails lla and lib are formed in the usual manner into track circuited sections, the sections being indicated by a reference character T plus a distinguishing exponent to represent the relation to the wayside signals. The track relays for these sections are designated by the referen-ce character R plus an exponent corresponding to the associated track section, their connections to the track rails being shown by dotted lines. It is clear that the track relays thus provided constitute devices automatically responsive to traic conditions of the stretch. The signal control relays governed by the track relays and which in turn govern the operation of the wayside signals will be taken up and described more fully hereinafter. f

CS designates a central station from where an operator governs traiiic through the stretch by virtue of a centralized tramo control system which permits the operator to selectively govern the indications of the diierent wayside signals and preferably the positions of the track switches, such control system being carried out through the medium of eld stations @FS and BFS located adjacent the track switches GSW and 8SW, respectively, and line wires X, Y and Z extending from the central station CS to the field stations. It will be understood that additional eld stations may be provided at selected points along the stretch and also along the railway outside of the stretch shown in the drawings, the line wires X, Y and Z being extended to such additional field stations. Other than certain relays to be referred to later, the C. T. C. system apparatus located partly at the central station CS and partly at the eld stations EFS and SFS is not shown since this apparatus forms no part of my invention and it may be any one of several types. One type of C. T. C. apparatus that may be used is that described and claimed in the United States Letters Patent No. 2,062,839 granted December 1, 1936 to Clarence S. Snavely for Selective controlling and indicating apparatus. It is deemed sumcient for the present application to pointout that the operator at the central station CS can selectively control the relays RI-IS and QLHS associated with the field station SFS, and the relays SRI-IS and ELI-IS associated with the field station SFS by sending code impulses over the line wires X, Y and Z, of which line wires the wire Z is the common return wire and the wires X and Y are the code control wires. Although three line wires X, Y and Z are shown for the C. T. C. system, it will be understood the line circuits may include only two line wires or they may consist of more than three line wires, as desired. The significant thing regarding these line alveare wires, as far as this application is concerned, is the fact that these line wires are ordinarily strung o a pole line where they are exposed to storms and other hazards.

The code control relays SRI-IS and {LI-IS at the iield station GFS are utilized to control the signals located adjacent the track switch SSW by virtue of contacts operated by these relays being interposed in the control circuits for the signal relays in a manner to later appear. Likewise, the code control relays BRI-IS and SLI-IS at the field station BFS are utilized to control the signais located adjacent the track switch SSW by contacts of the relays being interposed in the control circuits for the signal relays.

The C. T. C. system preferably would also include apparatus for governing the position of the track switches BSW and 8SW by controlling the operation of power actuated switch machines designated as SSM and 8SM. The apparatus for governing the position of the track switches is not shown for the sake of simplicity since it is not involved in the present invention. According to usual practice, the switch machines 6SM and rSM would be of the dual type provided with hand levers for operation by trainmen at the switch, with the result that operation oi the switches may be eiected in the event of a failure of the C. T. C. system.

To remove the signals from control of the C. T. C system, a transfer or switching relay and a repeater' relay are provided at each field station, a transfer relay AB and a repeater relay PB being located at eld station FS, and a transfer relay SAB and a repeater relay BPB being located at the iield station SFS. The transier relays GAB and SAB are normally energized over a line circuit supplied with power at the central station CS, the operating windings of these two relays being connected with the line circuit. As shown in Figs. la and 1b, this line circuit includes a line wire L and the common return wire Z of the C. T. C. system, the circuit being traced from the B terminal of any convenient source of current, such as a battery not shown, over one blade o a double-pole singlethrow switch 3 located at the central station CS, line wire L, winding of relay GAB at station FS or winding of relay SAB at station BFS, common return wire Z, wire the other blade of switch 3, and to the C terminal of the current source. The line wire L is mounted on the pole line in a manner so as to be exposed to the vsame hazards as the other wires X, Y and Z. It follows that the relays @AB and BAB are normally energized and picked up but that failure of either the line wire L or Z, or operation of switch 3 causes the relays to be deenergized and released. Thus, any weather condition or hazard that destroys the line circuits of the C. T, C. system would, ordinarily at least, cause the transfer relays at the eld stations to become deenergized.

Looking at field station SFS, the repeater relay PB is provided with a simple pick-up circuit including the back contact of the transferrelay GAB, and with a stick circuit including the B terminal, back contact l2 of the code control relay SRHS, back contact i3 of code control relay GLHS, front contact l and winding of relay iPBy and to the C terminal. At station GFS, the repeater relay BPB is provided with a pick-up circuit and a stick circuit, the pick-up circuit including back contact I5 vof the transfer relay SAB, and the stick circuit serially including back contact f6 of code control relay 8LI-IS and back contact l1 of code control relay 8RI-IS. It is to be seen,l therefore, that the repeater relays BPB and 8PB are each normally deenergized and are each picked up upon release of the associated transfer relay. Once picked up, the repeater relay at each lield station is retained energized until one of the code control relays at the same station is picked up. In other words, a failure of a line Wire that causes the transfer relays at the field stations to be released causes, in turn, the repeater relays at each of the field stations to be energized and picked up, and the repeater relays are retained energized subsequent to reclosing of the line circuit until a code control relay of the C. T.

C. system is selectively energized and picked up by the operator at the central station sending the necessary code. It is also clear that the operator at the central station can control the transfer andrepeater relays at the different eld stations by operating the switch 3, the repeater relays at the field stations being released subsequent to reclosing of the switch 3 by the operator sending a code to pick up a code control relay at the same field station. The manner whereby contacts of the repeater relays BPB and 8PB arel interposed in the control circuits for the signal control relays for removing the signals from the control of the C. T. C. system and permitting the signals to be operated in an A. P. B. system will be pointed out as the control circuits for the signal control relays are taken up and described. f

The relays and circuits governing the operation of the signals are, as previously set forth, jointly governed by traic conditions through the medium of the track relays and by the C. 'I'. C. system through the medium of the code control relays at the eld stations. The circuits for the signal control relays have been illustrated by showing, in most cases, the circuit controlling contact lingers of the various relays remote from the windings of the relays. The relation of each such contact finger with its relay is indicated by placing the reference character of the relay just above the contact finger, and showing the contact nger in the position corresponding to the normal energized or deenergized condition of the relay. In the present instance, the relays and circuits are those required to eiect a wellknown type of A. P. B. system in present-day use. This being so, it is believed suflicient to describe the signal control relays and their control circuits only in so far as is necessary for a full understanding of my invention. It is understood, of course, that the invention is not limited to the A. P. B. type of wayside signal system and is useful for other arrangements of signals governing traffic either on single track or multiple track railways. Furthermore, the wayside apparatus may be that required for a cab signal system or for a combination cab and wayside signal system.

Each signal is provided with a home relay designated by the reference character H, plus a prefix corresponding to the signal. The Ventrance signals 6Ra and 8La are further provided withv a special home relay identified as HT, plus a prefix corresponding to the signal. 'I'he special home relays RaI-IT and BLaHT and the home relays GLaI-I and RaH for the starting signals BLa and 8Ra each have associated therewith a slow acting repeater relay designated by the reference character A, plus a prefix corresponding to the reference character of the associated relay. The intermediate signals I, 2, 9 and I0 are, in addition to the home relays, each provided with a directional stick relay designated by the reference character S, plus a prefix corresponding to the signal, and each of the associated home relays is provided with a slow acting repeater re-l lay designated by the reference character SA, plus a prefix corresponding to the reference character of the associated signal.

The immediate operating circuits for the several signals are in each case completed over contacts of the home and special home relays of the signal. However, such operating circuits are notvv shown in order not to unduly complicate the drawings since the signal operating circuits form no part of the invention, and it will be understood they would be in accordance with standard practice.

In accordance with usual practice in C. T. C. systems, the apparatus for the signals adjacent the switch BSW includes the usual signal repeater relays and approach locking relays. A signal repeater relay BRM checks the position of the signal 6R11., 6R?) and the intermediate signal 2 by checking the position of the control relays of these signals. A signal repeater relay SLM checks the position of the signals SLa, 6Lc and the entrance signal 8La by checking the position of the control relays of the associated signals. To be specic, the signal repeater relay ERM is controlled over a circuit extending from the B terminal of the current source, polar contact 63 of the home relay 2H, back contact 64 of home relay RbI-I, back contact 65 of home relay RaH, winding of relay SRM, and to the C terminal of th-e current source, a back Contact 55 of the repeater relay 2SA completing a shunt path around the polar contact 63. The signal repeater relay BLM is provided with a control circuit extending from the B terminal over polar contact 61 of special home relay 8LaI-IT, back contact 68 of home relay LcH, back contact ES of home relay GLaI-I, winding of relay ELM, and to the C terminal, a back contact 'l0 of relay LaHTA completing a branch path around the polar contact 61. An approach locking relay BRK associated with eastbound traic approaching the switch BSW is controlled over the usual circuit network provided for such locking relays and which network is indicated at 1I. An approach locking relay BLK associated with westbound traffic is governed over a similar circuit network indicated at 12. 'Ihese two circuit networks ll and 12 are not shown, since their specific arrangement forms no part of the invention, and may be any one of several well-known types.

`The control circuits for the signal repeater relays 8RM and SLM which check the signals at switch 88W are similar to the circuits for the relays 6LM and GRM, respectively, and will be readily understood by an inspection of the drawings. The approach locking relays BRK and 8LK associated with traflic approaching the switch BSW are governed over circuit networks similar to the networks provided for relays ERK and 6LK.

Looking at the home relays BLaI-I and LcI-I for the starting signals SLa and GLC, a control circuit selectively governs these relays in accordance with the position of the switch BSW, the relay SLaH being selected when the switch is set for traic on the main track, and the relay BLcI-I being selected when the switch is reversed for a movement to the passing siding. Starting at the B terminal shown at the upper left-hand portion of Fig. 1a, this control circuit may be traced over front contact 20 of relay ISA, back contact 2l of relay 2S, front contact 22 of code control relay GLHS, front contact 23 of relay SRK, contact 24 operated by the switch GSW and closed with the switch normal, winding of relay LaI-I, front contact 25 of track relay S'IRa, front contact I8 of track relay ZIRbJ front contact 26 of relay ERK, front contact 21 of lcode control relay ELI-IS, back contact 28 of relay 2S, front contact 29 of relay ISA, front contact 30 of track relay Z'IRa, and to the C terminal. This control circuit is pole-changed over contacts of the relays IS and ISA, as will be readily understood by an inspection of Fig. la. With switch ISSW reversed and the contact 24 moved to the dotted line position, the relay ELOI-I is selected. When the home relay LoLI-I is energized and picked up, its associated repeater relay BLaHA is energized over a simple circuit including front contact 6I of relay BLaH. It follows that the relays SLaI-I and BLCH, and, in turn, the corresponding signals BLUl and SLC, are governed by traic conditions to the left of switch BSW and also by the code control relay GLI-IS. Specic attention is directed to the fact that the front contacts 22 and 2'I of the code control relay ELI-iS are provided with by-paths governed by the repeater relay SPB at the field station GFS. The by-path around front contact 22 of relay GLI-IS includes front contact 3l of relay BPB, and the by-path around the front contact 21 includes the front contact ,32 of relay BPB. Consequently, a condition of the line circuits for the C. T. C. system which causes the repeater relay PB to be picked up in the manner described herinbefore removes thev home relays GLwH and eLcI-I, and, in turn, their corresponding signals, from the control of the C. T. C. system and permits these relays and their signals to operate automatically in response to traic conditions.

The home relays SRaH and BRCH for the starting signals BRa and 8Rc are provided with a control circuit similar to the control circuit just described for the -home relays of the signals La and GLC. Starting at the B terminal shown at the upper right-hand portion of Fig. 1h, a control circuit extends over front contact 33 of track relay STR, front contact 34 of relay iSA, back contact 35 of relayiSS, iront contact 36 of code control relay SRHS, front contact 31 of relay 8LK, contact 38 operated by the switch iSW and closed when the switch is normal, winding of relay RaH, front contact 39 oi track relay 8TRa, front Contact 40 of relay STRU, front contact 4I of code control relay SRHS, back contact 42 of relay=9S, front contact `43 of relay MSA, and to the C terminal. YThis control circuit is pole-changed over contacts of the relays IS and IIlSA, as will be readily understood by an inspection of Fig. 1b'. Also, .when the switch SSW is reversed and contact 38 moved to the dotted line position, the relay SHCI-I is selected. When the home relay 8RaII is picked up, its associated slow acting relay SRaHA is energized over a simple circuit including front contact 52 of relayiBRaH. It follows `that the relays SRaH and 'IiRcI-I, and, in turn, their associated signals 8Ra and SRC, are governed by traic conditions to the right vof switch'SW and by the code control relay 8RHS of the C'. T. C. system. Special attention is directed to the fact that the front contacts 36 and 4I of the code control relay IIRHS are. each provided with a by-path controlled by the repeater relay 8PB at the ield station LSFS, :the :by-path for the /front contact 36 including front contact 44 of relay 8PB, and the by-path for the front contact 4I including front contact 45 of relay SPB. Consequently, any condition as to the line circuits of the C. T. C. system that causes the repeater relay 8PB to be energized and picked up removes the home relays BRaI-I and SRcH, and, in turn, their signals, from the control of the'C. T. C`. system and permits these relays and signals to operate automatically in accordance with traic conditions. y,

Referring now to the control circuits for the relays of the entrance signals Ra, and 6R11, and looking rst at the special home relay RaHT, a control circuit extends from the B terminal over front contact 46 of relay BLM. front contact 4l of relay SLK, front contact 48 of track relay BTRa, back contact 49 of relay BRaI-IA, front contact 50 of track relay TRc, front contact 55| of track relay ITRb, winding of relay RaI-IT. back Contact 52 of relay RaHA, front contact 53 of track relay STRa, front contact 54 of relay BLK, front contact 55 of relay SLM, and to the C terminal. This control circuit is pole-changed over contacts of the slow acting relay -8RaHA, and is supplied with current over contacts 56 and 5l when the switch 65W is reversed. With relay GRaHT picked up, the associated slow acting repeater relay SRaHTA is supplied with current over front contact 58 of relay ERaHT.

The important feature concerning this control circuit for the special home relay RaHT, as far as my invention is concerned, lies in the fact that the repeater relay @PB at Vthe eld station 8FS governs by-paths around the contacts of the signal repeater relay BLM and the approach locking relay 8LK interposed in this control circuit. The fron-t contact 59 oi relay BPB completes a by-path around front contacts 46 and 4-1 of relays SLM and BLK, respectively, and the front contact 6E) oi relay SFB completes a by-path around the front contacts 54 and 55 of relays SLK and 8LM, respectively. Hence, a condition of the C. T. C. system that results in the repeater relay SPB being picked up removes the special home relay SROLHT from all control by the apparatus of the C. T. C. system and permits this relay to be governed automatically by traic conditions.

The control circuit for the home relays RaH and GRDH for the starting signals 6R11 and @Rb extends from the Br terminal over front contact i3 of code control relay @Rl-IS, front contact i4 of relay ELK, contact 'I5 operated by switch SSW and closed when the switch is normal, front contact I6 of the repeater relay RaHTA for the associated special home relay @Ra-IT, winding of relay -6RaI-l, front contact 'il of track relay STRa, front contact I8 of code control relay RHS, and to the C terminal. When the switch GSW is reversed and contact 'I5 is moved to the dotted line position, the relay RbH is energized. Thus, the home relays Ra-I and RbH, as well as the special home relay RaHT, are controlled by traiic conditions to the right of lthe, switch BSW, andthe home relays are also controlled directly by the C. T..C system ,through the medium of the code control relay GRES. The special feature to be here notedis the fact that by-paths are provided aroundthe front contacts AI3 and .18 of the code control relay RHS, the by-path around contact 'I3 being completed over front contact I9 of the repeater relay vPB, and the by-path around front contact 1,8 being comvis pleted by the front contact 89 of the repeater relay 6PB.

Again, it is to be noted that a condition of the C. T. C. system that causes the repeater relay `|PB to be picked up removes the home relays ERaI-I and (RbI-I, and, in turn, their associated signals, from control of the S. T. C system and permits these relays and signals to operate auto- `Inatically in accordance with traffic conditions.

Turning now to the special home relay SLaI-IT associated with the entrance signal SLa, a control circuit extends from the B terminal over front contact 8| of relay BRM, front contact 82 of relay SRK, front contact 83 of track relay BTRa, back contact 84 of relay BLaI-IA, front contact 85 of track relay GTRb, front contact 86 of track relay STRG, winding of relay SLaHT, back contact 8l of relay LaI-IA, front contact 88 of relay GI'Ra, front contact 89 of relay BRK, front contact 99 of relay BRM, and to the C terminal. With the relay SLaI-IT picked up, its repeater relay SLaI-ITA is supplied with current over front contact 9| of relay LaHT.

To remove relay LaHT from control of the signal repeater relay BRM and the approach locking relay SRK associated with the C. T. C. system, the front contacts 8| and 82 of relays GRM and BRK, respectively, are provided with a bypath including front contact 92 of relay BPB, and the front contacts 89 and 99 of relays SRK and BRM, respectively, are provided with a bypath including front contact 93 of relay BPB.

, The home relays 8LaI-I and SLbH provided for the entrance signals 8La and BLZ: are governed over a control circuit traced from the B terminal, front contact 94 of code control relay 8LHS, lfront contact 95 of relay SLK, contact 9B operated by switch 88W and closed with the switch normal, front contact 91 of relay 8LaHTA, winding of relay 8LaI-I, front contact 98 of track relay 8TRa, front contact 99 of code control relay LI-IS, and to the C terminal. With the switch 8SW reversed and the contact 96 moved to the dotted line position, the relay BLbI-I is energized.

It is to be observed that the front contacts 94 and 99 of the code control relayLHS are provided with by-paths, the by-path around front contact 94 being completed at front contact |99 of repeater relay 8PB1, and the by-path around front contact 99 being completed at front contact |9| of relay BPB. It follows that the special home relay SLaI-IT and the home relays 8LaI-I and 8LbI-I are removed from the control of the C. T. C system, and the signals 8La and 8Lb are operated automatically by traic conditions in the event a condition arises in the C. T. C. system'that results in the repeater relays BPB and BPB being energized and picked up.

The directional stick relays and the repeater relays provided for the intermediate signals I, 2, 9 and I9 are in each case controlled over circuits ofthe standard form, and it is thought unnecessary to discuss these circuits in detail since they will be readily understood from an inspection of the drawings.

The control circuit for the home relay 2H of signal 2 is shown at the lower left-hand portion of Fig. la. This circuit for the relay 2H is that of standard form and need not be described in detail except to point out that front contacts |92 and |93 of signal repeater relay SLM and approach locking relay SLK, respectively, are interposed in one side of the circuit, and front contacts |94 and |95 of relays GLM and SLK,

respectively, are interposed in the other side of the circuit. That the relay 2H may operate in response to traiic conditions only in the event of a failure of the C. T. C. system which might effect the operation of the relays GLM and 611K, the front contact |98 of repeater relay BPB completes a by-path around the front contacts |92 and |93, and the front contact |91 of relay SPB completes a by-path around the front contacts |94 and |95.

The control circuit for the home relay 9H of signal 9 is shown in the lower right-hand portion of Fig. 1b. This circuit is in accordance with standard practice and need not be described eX- cept to point out that the front contacts |98 and |99 of signal repeater relay SRM and approach locking relay SRK, respectively, are interposed in one side of the circuit, and front contacts H9 and of relays 9RM and 8RK, respectively, are interposed in the other side of the circuit. In order that the home relay 9H may operate in re- Sponse to tralic conditions only in the event a failure of the C. T. C. system eiects the operation of the relays SRM and SRK, a by-path around front contacts |98 and |99 is completed at front contact ||2 of the repeater relay 8PB, and a bypath around front contacts ||9 and is completed at front contact |63 of relay BPB.

A marker lamp is mounted on each of the starting and entrance signals to indicate to the trainmen when the signals are removed from the control of the C. T. C. system and are being operated in accordance with the A. P. B. system. In Fig. la,'the marker lamps ||4, ||5 and i6 are mounted on the usual masts of the signals 6R41, SLC and BLCL, respectively. These marker lamps are connected in parallel in a circuit completed over front contact i Il of the repeater relay PB. Thus, a condition of the C. T. C. system that results in the repeater relay SPB being picked up to remove the signals from control of the C. T. C. system in the manner described hereinbefore also causes the marker lamps H4, ||5 and ||6 to be illuminated.

In Fig. lb, marker lamps H8, ||9 and |29 are mounted on the masts of signals 8Ra, 8Rc and BLa, respectively, and are connected in parallel in a circuit completed at front contact |2| of repeater relay BPB. Thus, a condition of the C. T. C. system that results in the repeater relay BPB being picked up to remove the signals from control of the C. T. C. system also causes the marker lamps ||8, ||9 and |29 to be illuminated to indicate to the trainmen that the signals are being operated by the A. P. B. system.

In Fig. 2, the transfer relays at the field stations are controlled over a line circuit independent of the line wires of the C. T. C. system. This line circuit comprises two line Wires Li and L2 which are connected with the B and C terminals of the current source over the switch 3 at the central station CS, and across which line wires the operating winding of the transfer relay GAB at station SFS is connected. The transfer relays at other eld stations would be connected across the line wires L| and L2 in the same manner as shown for relay EAB of field station BFS. The line wires LI and L2 would be disposed between the central station and the eld stations in a manner so as to be exposed to the same hazards a'stick circuit including back contacts of the code `side of theswitch 3, and to the C terminal.

control relays SRHS and SLI-IS, `the `same asin Fig. .1a. It isfclear that, with the `line circuit and ltransfer relays of Fig. 2 provided for the signal system of Figs. 1a` and 1b, a condition-of the line ycircuits t-hat results in 4the transfer relays being deenergzed and the associated repeater relays picked up will remove the signals from the control -of theC. T. C. system and cause the signals to be operated automatically by the A. P. B. system in the same manner as described for Figs. 1a and 1b.

In Fig. 3, the transfer Irelays are controlled over a grounded line circuit including a line wire :L3 .disposed on the pole line so as to be exposed to .the same hazards as the line wires of the C. T. C. system. The B terminal of the current source is connected over switch 3 to the line wire L3, and the `C terminal is connected with a ground electrode 1.22. At eld station SFS, transfer relay BAB has one terminal rof its operating Winding connected with the line wire L3 and the other terminal of its winding connected with a ground velectrode 123. The transfer relay at field station 8F55 would 4be connected between'fthe'line wire L3 and ground inthe same manner Ias transfer vrelay BAB. Thus,in Fig. 3, theftransfer relays are normally energized land are deenerglzed upon a failure of the line-circuitsor vby the operation of the switch 3 at the central station. The repeater'relay l(PB of Fig. 3 is controlled in the same manner as described for Fig. la. Consequently, with the apparatus of Fig. 3 applied tothe signal system yof Figs. la, and lbi, a failure of theline circuit that results in the deenergizing of the transfer relays andthe picking up of the associated repeater relays will remove the signals from the control of the C. T. C. vsystem and permit them to be operated `by the A. P. B. system.

I-n Fig. 4, vthe transfer relays are serially interposed in a line circuit which is grounded. This line circuit extends from Vthe B terminal of the current source over one sideof the switch 3, line wire L4, operating winding of transfer relay SAB, vline wire L5, operating winding of transfer relay 8AB, ground electrodes |24 and |25, the other The line wires L4 and L5 are disposed on the pole l-ine :so as to be exposed to the same hazards as the wiresX, Y and Z. It is clear that, with the apparatus constructed in the manner shown in Fig. 4, .the transfer relays are normally energized and are deenergized by a failure of the `line circuits vor ,by operation of the switch 3. The transfer relays of Fig. 4 are effective to pick up the associated repeater relays, the same as in previous cases, and hence, with the'apparatus of Fig. 4 applied lto the signal system of Figs. la and 1b; a condition of the line circuits of the C. T. C. system that causes the transfer relays `to be deenergized is effective to remove the signals from controlof the C. T. .C. system and permit them to be operated by the A. P. B. system.

Although I have herein shown and described only a Vfew forms of apparatus embodying my invention, it is .understood that various changes and modications may be made therein Vwithin the scope of the appended claims without departing from the spirit and scope of my invention.

Having vthus described my invention, what I claim is:

1. In combination, a stretch of railway track, a track relay responsive to traffic conditions of said stretch, a signal for governing trafc through the stretch, -a remotely controlled relay located along the stretch, a central station, a vcircuit including a line wire for controlling said remotely controlled relay from-said centralstation, a signal relay for governing the operation of the signal, a control circuit for said signal relay including a front contact-of the track relay and a'front contact of the remotely controlled relay, a transfer relay, another circuit including said line wire for normally energizing said transfer relay, a repeater relay, a pick-up circuit for the repeater relay including a back contact of the transfer relay, a stick circuit for the repeater relay including a back contact of the remotely controlled relay, and a, by-path around the front contact of the remotely controlled relay interposed in said control circuit including a front contact of said repeater relay.

2. In combination, a section of railway track, a track circuit for the section including ya track relay, two signals one adjacent each end of the section for governing rtraiic in opposite directions through the section, a home relay for each signal for operating the signal, a eld station adjacent said section, a control relay Afor each signal at said eld station, an energizing circuit lfor each home relay including a front contact of the back relay and a front contact of the associated control relay, a central station, a circuit for selectively controlling said control relays including a pair of line wires extending from the central station to the eld station, a transfer relay and a repeater relay at said iield station, a pick-up circuit for the repeater relay including a back contact of the transfer relay, a stick circuit for the repeater relay including a back contact of each of said control relays, a normally closed circuit for energizing said transfer relay including another line wire extending from the central station to the eld station .and positioned so as to be exposed to the same hazards as said pair of line wires, andby-paths one around the front contact of the control relay interposed in each of said energizing circuits and each by-path including a front contact of said repeater relay.

3. In combination, a section of railway track, a track circuit for the section including a track relay, two signals one adjacent each end of the section for ,governing `traiiic in opposite directions through the section, a field station adjacent said section, two control relays at said ield station one for each of said signals, .operating means for each signal controlled jointly by the associated control relay and Vby the track relay, a central station, a circuit for selectively controlling said control relays from said central station including a line Wire, `a transfer relay and a repeater relay at the field station, a normally closed circuit for energizing said transfer relay including said line wire, means including front contacts of said repeater relay to remove said signals from control of the control relays and to permit them to be operatedby the track relay alone, a pick-up circuit for the repeater relay including a back contact of the transfer relay, and a stick circuit for said repeater relay including a back contact of each of the control relays.

4. In combination, a stretch of railway track, automatic means responsive to trafiic conditions in said stretch, a signal for governing tralc through the stretch, a remotely controlled relay located along the stretch, a central station, a line circuit for controlling said relay from said central station, operating means for said signal controlled jointly by said automatic means and said relay, a transfer relay, another line circuit extending between said stretch and said central station for normally energizing said transfer relay, a repeater relay, a pick-up circuit for said repeater relay including a back contact of the transfer relay, arstick circuit for said repeater relay including a back contact of said remotely controlled relay, and means including a front contact of the repeater relay to remove said signal from control of said remotely controlled relay and to permit it to be controlled by said automatic means alone.

5. In combination, a section of railway track, a track circuit for said section including a track relay, a signal for governing trafiic through the section, a home relay for governing the operation of said signal, a control relay located adjacent Said section, an energizing circuit for said home relay including a front Contact of the track relayr and a front contact of the control relay, a central station, a line circuit extending from said central station to said section for at times energizing said control relay, a transfer relay and a repeater relay, a pick-up circuit for the repeater relay including a back contact of the transfer relay, a stick circuit for said repeater relay including a back contact of said control relay, another line circuity extending from said central station to said section for normally energizing said transfer relay, and a by-path around the front contact of said control relay interposed in said energizing circuit of the home relay including a front contact of said repeater relay.

6. In combination, a stretch of railway track formed into insulated track sections, wayside signals located at selected points along the stretch for governing traic through the stretch, automatic apparatus controlled by traffic conditions of the stretch and operating to govern the wayside signals as required for an automatic wayside signal system, code controlled relays located at selected points along the stretch, a central station, means including a line circuit for selectively controlling said code controlled relays from said central station, circuit means governed by said code controlled relays to modify the control of said automatic means over the signals as required to operate the signals as a centralized traic control system, a plurality oi' switching means one located at each selected point for the code controlled relays and each including a transfer relay and a repeater relay, means including another line circuit for normally energizing each of said transfer relays from the central station, a pickup circuit for each repeater relay including a back contact of the associated transfer relay, a stick circuit for each repeater relay including a back contact of at least one of the code controlled relays at the same location, and means controlled by said repeater relays when energized to remove the modification effected by said code controlled relays over the control of said automatic means.

CLYDE L. OTT. 

